let user = {"name": "张三", "age": 28};
let obj = user;

console.log("-------------------------------------------------------------------------------------");
obj.sex = "男";
console.log("obj:", obj);
console.log("user:", user);

console.log("-------------------------------------------------------------------------------------");
user.sex = "女";
console.log("obj:", obj);
console.log("user:", user);

console.log("-------------------------------------------------------------------------------------");
obj = {"class":"aaa"};
console.log("obj:", obj);
console.log("user:", user);